1. Field of the Invention
The present invention pertains to truck trailers for hauling relatively large, dense objects, and in particular to heavy objects such as steel coils which are heavy, yet relatively delicate, and which have rounded surfaces.
2. Description of the Related Art
Different types of products being shipped today over the road require special handling considerations. For example, special considerations must be given when hauling steel products by truck. Steel products are shipped in a variety of different configurations, including flats, rounds, and coils. In the past, it has been found desirable to have a single type of truck trailer haul the various steel products. So-called platform trailers have been employed to ship the various types of steel products. Flats and rounds are typically cut in fairly long lengths, and are typically laid along the major axis of the platform trailer.
Outside of weight considerations and considerations of trailer loading capability, careful attention must be paid to avoid shifting the steel load on the platform trailer, particularly when the trailer, travelling on the highway at customary speeds, is brought to a sudden stop. The shipping of steel coils raises other considerations, in addition to those already mentioned. Steel coils, by their nature, have rounded surfaces on which the coils can roll. Thus, if the coils should become dislodged from a moving trailer it is possible that the coils will roll into traffic before coming to rest. Further, even when the coils are securely restrained on a platform trailer, great care must be exercised to insure the coils do not rock back and forth on their rounded surfaces, thereby being allowed to build up momentum which might overtax the securing devices.
Further considerations are raised when hauling steel coils, which are unique to that steel product configuration. Basically, the steel coil comprises a winding of steel sheeting which is coiled for convenient bulk transport. With current manufacturing techniques, including "just-in-time" techniques, and zero defect manufacturing tolerances, consumers of the steel coils have demanded that the coils be shipped without damage of virtually any kind, so that the coils can be unloaded and set up at the last minute in a manufacturing operation. The steel coils are quite massive, and are typically supported on end, along a tangent line to the curved surface of the coil. Due to the mass of the coil, this results in a relatively high pressure being applied to local portions of the steel coil, which is amplified as the coil shifts or rocks during transport. Considerable attention has been paid to the special handling required for steel coils, and an improved motor vehicle trailer has been sought.